In order to achieve good efficiency values for the elongation of the mechanical valve clearance compensation element, it is necessary to use a thread with a large pitch, advantageously an angle greater than 12°. A good efficiency value in the case of elongation makes possible low spring forces and therefore low contact forces in the root circle of the cam, which leads to low friction losses in the valve drive.
If a thread with a corresponding pitch is cut on an adjusting bolt, the guide length in the sleeve is lost partially or even completely, because in the case of thread cutting, a thread run-out must always be taken into consideration that corresponds to at least 1×the pitch.
Such a valve clearance compensation element is known from WO 2009/096353 A1. In order to compensate the thread run-out, the sleeve and the adjusting bolt are built relatively long, wherein also the distance of the support head from the thread is long and the support head is limited in diameter. Because the adjusting bolt has a continuous thread and the thread always has a radial play, the guide of the transfer element on the support head is not provided with sufficient reliability, so that there are variations and inaccuracies in the valve drive.
Furthermore, a valve clearance compensation element is known, DE-38 83 547 T2, in which grooves are machined into the thread of the adjusting bolt, in order to increase the self-locking. This, however, produces the disadvantage that there is the risk of increased wear and increased clearance, which likewise leads to variations and inaccuracies in the valve drive, because the thread is the sole guidance of the adjusting bolt in the sleeve.